Mortars for Brickwork – Typical lime:sand proportions used in construction For general brick masonry work, which of the following lime–sand mortar proportions (lime:sand by volume) is commonly adopted in practice?

Introduction / Context:
Lime mortars remain relevant for heritage, low-rise, and breathable masonry. The proportion of lime to sand controls workability, strength gain, permeability, and compatibility with clay bricks. A commonly taught proportion for general brickwork is 1:3 (lime:sand) by volume for fat lime mortars, with adjustments based on lime type and sand grading.

Given Data / Assumptions:

• Use of fat (non-hydraulic) lime unless specified otherwise.
• Clean, well-graded sand.
• General brick masonry, not high-strength structural concrete.

Concept / Approach:

Mortar proportioning balances binder and aggregate so that the mix fills joints, adheres to units, and cures without excessive shrinkage. Too rich (1:1, 1:2) increases cost and shrinkage; too lean (1:4, 1:5) reduces cohesion and early strength. A 1:3 mix provides a practical middle ground frequently cited in textbooks and schedules for lime mortars in brickwork.

Step-by-Step Solution:

Verification / Alternative check:

Schedules of rates and handbooks list 1:3 as a prevalent proportion; site trials fine-tune water content and sand grading.

Why Other Options Are Wrong:

1:1 and 1:2 are unnecessarily rich for general brickwork; 1:4 or 1:5 can be too weak or porous for structural joints without additives or hydraulic lime.

Common Pitfalls:

Confusing lime mortar with cement–lime or pure cement mortars; not accounting for lime type (fat vs hydraulic) and sand grading.

Final Answer:

1:3